The Road to Quantum Gravity.

...........When applied to the whole universe, de Sitter special relativity is able to predict,from the current matter content of the universe, the value of cosmological constant (lambda). It gives, furthermore,an explanation for the cosmic coincidence problem.When applied to study the propagation of ultra-high energy photons, it gives a good estimate for the recently observed delay in high energy gamma-ray flares coming from the center of the galaxy Markarian 501. If this delay is a manifestation of the small-scale fluctuations in the texture of spacetime, predicted to exist at very high energies, de Sitter relativity can be seen as a new paradigm to approach quantum gravity..............

............Even though conformal symmetry is not an exact symmetry at low energies, according to de Sitter special relativity it naturally becomes the relevant symmetry at ultra-high energy densities. In fact, the higher the energy density, the higher the value of lambda, the higher the importance of conformal symmetry. Near the Planck energy, the local value of lambda will be very large, and the local de Sitter space will approach a conespacetime, which is transitive under proper conformal transformations only. Under such extreme conditions, physics becomes conformal invariant, and the proper conformal current will be conserved....

Seems to underly a lot of the observational portion of the piece. The thinking seems sound at high energies, but I don't find the MAGIC data convincing, although I respect their free admission of possible interference.

This seems like a lot to justify on the basis of choosing a possible source of delay when others with less global implications may well exist.

Seems to underly a lot of the observational portion of the piece. The thinking seems sound at high energies, but I don't find the MAGIC data convincing, although I respect their free admission of possible interference.

This seems like a lot to justify on the basis of choosing a possible source of delay when others with less global implications may well exist.

..........We stress here that our most conservative limits, a and b in Table 1,
rely on very different and largely independent analysis, yet still give a
very similar limit, of [tex]\xi[/tex]1>.1.2. This lends considerable support to this
result, and makes it more robust and secure than for each of the methods separately.............

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............Giovanni Amelino-Camelia of the University of Rome La Sapienza believes that the latest work points to the coming of age of the field of quantum gravity phenomenology, with physicists finally able to submit theories of quantum gravity to some kind of experimental test. "Nature, with its uniquely clever ways, might have figured out how to quantize space–time without affecting relativity"..............

We stress here that our most conservative limits, a and b in Table 1,
rely on very different and largely independent analysis, yet still give a
very similar limit, of [tex]\xi[/tex]1>.1.2. This lends considerable support to this
result, and makes it more robust and secure than for each of the methods separately.